Short PUCCH Signaling for TDD Uplink Control
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Solution Overview
Problem
In wireless communication systems, particularly in shared communication mediums like unlicensed frequency bands, there is a challenge in efficiently managing uplink control channel signaling to minimize cross-link interference and optimize resource usage, especially when coexisting with other Radio Access Technologies like Wi-Fi, due to stringent Listen-Before-Talk requirements and potential for contention.
Innovation Solution
The implementation of a short Physical Uplink Control Channel (sPUCCH) that spans a subset of symbol periods in the time domain and interlaces across subcarriers in the frequency domain, allowing for adaptive duration and payload configuration, enabling more opportunistic and efficient use of resources, including contention-exempt access during special subframes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional PUCCH channel occupies the full subframe duration, then reliable control signaling is achieved, but latency is increased and spectral efficiency is reduced
Solution Approach 1:
The patent segments the control channel transmission by introducing a short PUCCH format that transmits control information in a shortened duration within the subframe, rather than occupying the full subframe. This segmentation allows faster transmission while maintaining essential control functionality, thereby reducing latency without completely sacrificing reliability.
Solution Approach 2:
The patent implements dynamic adaptation of PUCCH duration based on traffic conditions and system requirements. The network can configure different PUCCH formats and durations adaptively, allowing the system to switch between shorter durations for low latency and longer durations for higher reliability based on current operational needs.
2Loss of time
If short TTIs are used to reduce latency, then HARQ RTT is reduced and link adaptation improves, but processing time is reduced to near decoding limits
Solution Approach 1:
The patent prepares control information and resources in advance for short TTI operation. By pre-configuring short PUCCH formats and preparing control data before the shortened transmission window, the system can meet the tight processing deadlines without excessive complexity during the actual transmission phase.
3Reliability
If PUCCH signaling occupies full subframes in shared unlicensed bands, then control information is reliably transmitted, but contention with Wi-Fi and other RATs increases
Solution Approach 1:
The patent segments control channel transmissions into shorter durations that can be more efficiently scheduled in shared spectrum. By transmitting control information in brief intervals rather than full subframes, the system reduces the time occupation in unlicensed bands, thereby decreasing contention with Wi-Fi and other RATs while maintaining control signaling reliability.
Solution Approach 2:
The patent employs periodic short PUCCH transmissions that are scheduled at specific intervals rather than continuous full-subframe occupancy. This periodic approach allows other systems like Wi-Fi to access the medium in between, improving coexistence and overall spectral efficiency in shared unlicensed bands.
Data Source
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AI summary
Techniques for control channel signaling on a shared communication medium are disclosed. An access point or an access terminal may communicate over a communication medium in accordance with a Time Division Duplex (TDD) frame structure defining a set of subframes that each span a plurality of time-domain symbol periods. The access point may transmit and the access terminal may receive receive control information via a short Physical Uplink Control Channel (sPUCCH) on one or more of the subframes in a portion of the subframe configured for uplink signaling. The sPUCCH may comprise one or more pilot symbols and one or more payload symbols that collectively occupy a subset of less than all of the symbol periods in each of the one or more subframes.